[openstack-dev] [libvirt] [nova] The risk of hanging when shutdown instance.

zhang bo oscar.zhangbo at huawei.com
Tue Mar 31 03:37:04 UTC 2015

On 2015/3/31 4:36, Eric Blake wrote:

> On 03/30/2015 06:08 AM, Michal Privoznik wrote:
>> On 30.03.2015 11:28, zhang bo wrote:
>>> On 2015/3/28 18:06, Rui Chen wrote:
>>>> <snip/>
>>>   The API virDomainShutdown's description is out of date, it's not correct.
>>>   In fact, virDomainShutdown would block or not, depending on its mode. If it's in mode *agent*, then it would be blocked until qemu founds that the guest actually got down.
>>> Otherwise, if it's in mode *acpi*, then it would return immediately.
>>>   Thus, maybe further more work need to be done in Openstack.
>>>   What's your opinions, Michal and Daniel (from libvirt.org), and Chris (from openstack.org) :)
>> Yep, the documentation could be better in that respect. I've proposed a
>> patch on the libvirt upstream list:
>> https://www.redhat.com/archives/libvir-list/2015-March/msg01533.html
> I don't think a doc patch is right.  If you don't pass any flags, then
> it is up to the hypervisor which method it will attempt (agent or ACPI).
>  Yes, explicitly requesting an agent as the only method to attempt might
> be justifiable as a reason to block, but the overall API contract is to
> NOT block indefinitely.  I think that rather than a doc patch, we need
> to fix the underlying bug, and guarantee that we return after a finite
> time even when the agent is involved.

So, may we get to a final decision? :) Shall we timeout in virDomainShutdown() or leave it to openstack?
The 2 solutions I can see are:
1) timeout in virDomainShutdown() and virDomainReboot(). in libvirt.
2) spawn a new thread to monitor the guest's status, if it's not shutoff after dom.shutdown() for a while,
   call dom.destroy() to force shut it down.  in openstack.

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